package com.bang.concurrency.example.commonUnsafe;

import com.bang.concurrency.annotations.NotThreadSafe;
import lombok.extern.slf4j.Slf4j;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;

/**
 * @Auther: Bang
 * @Date: 2019/9/30 23:06
 * @Description: StringBuilder 线程不安全
 */
@Slf4j
@NotThreadSafe
public class StringExample1 {

    // 请求总数
    private static int clientTotal = 5000;

    // 线程总数
    private static int threadTotal = 200;

    private static StringBuilder sb = new StringBuilder();

    public static void main(String[] args) throws InterruptedException {
        ExecutorService executorService = Executors.newCachedThreadPool();
        final Semaphore semaphore = new Semaphore(threadTotal);
        final CountDownLatch countDownLatch = new CountDownLatch(clientTotal);
        for (int i = 0; i < clientTotal; i++) {
            executorService.execute(() -> {
                try {
                    semaphore.acquire();
                    update();
                    semaphore.release();
                } catch (Exception e) {
                    log.error("e : {}", e);
                }
                countDownLatch.countDown();
            });
        }
        countDownLatch.await();
        executorService.shutdown();
        log.error("length = {}", sb.length());
    }

    private static void update() {
        sb.append("1");
    }

}
